Housing seventy-five thousand Manhattan Project workers and residents brought major challenges, including shortages of building materials and construction workers. Officials responded by using alternative materials such as gypsum board instead of wood for the walls of the Alphabet Houses and by providing less permanent accommodations for lower-wage employees. Plant workers, guards, firefighters, clerical personnel, construction workers, and others earning less than sixty dollars per week were assigned to the most temporary housing, trailers and hutments. African American workers were further segregated within the hutments, separate from the hutment area for single white men. Nearly four thousand trailers formed dense communities in present-day A.K. Bissell Park along Oak Ridge Turnpike and Illinois Avenue, in Gamble Valley, and near K-25. Like other housing areas, the trailer camps had stores, theaters, cafeterias, recreation and community buildings, and schools. Residents used shared bathhouses for showers, water collection, and other needs, filling a tank in each trailer daily because the trailers had no bathrooms. Most trailers were government owned and transferred to the project from other government agencies such as Tennessee Valley Authority, and many had been relocated by 1947.